1. Field of the Invention
The present invention relates to an apparatus and method for processing images which uses an optical filter to evaluate physical characteristics of an object.
2. Description of the Related Art
In the prior art, to pick up an image for image processing, an RGB camera is used to acquire color information. The color information acquired using the RGB camera is similar to human visual information and is thus characterized by being readily understood by human beings.
However, the color information is subjective information having an intermediate position in a human visual recognition process. It is thus difficult to make this information physically objective. That is, the human recognition of colors varies depending on an observation environment or a physical state. The recognition cannot be easily quantified or normalized. Thus, for example, if any lesion in a tissue sample is to be recognized, it is difficult to form a criterion.
In contrast, the spectral characteristic (hereinafter referred to as a spectrum) of a target is a physical characteristic inherent in the target and can be quantified as an objective value not affected by human subjectivity. A characteristic amount derived from the spectrum can be used as a criterion for objective determinations. A spectral image is obtained by acquiring spectral data on a target for each pixel and arranging the spectral data in image form. The spectral image contains important physical information on the target.
Much attention has long been paid to image processing using a spectrum. Various attempts have been made particularly in the field of diagnostic support.
For example, WO99/16353 discloses a method of diagnosing spectral biological image of eye which method comprises using an interferometer to divide light emitted to and reflected by the fundus of the eye and processing the resulting spectrum to recognize the concentration of hemoglobin in the retina blood vessels.
Further, other techniques for spectral processing include “Analysis of tissue samples using transmittance spectra—The method of considering the differences of dyeing conditions” (Fujii et al., Third “Color” Symposium for Digital Biological Medical Images). With this technique, the amounts of dyeing pigments contained in a pathological sample is estimated as a two-dimensional map on the basis of the spectral transmittance of the sample and the transmittances of the dyeing elements.